treewide: use blas and lapack

This makes packages use lapack and blas, which can wrap different
BLAS/LAPACK implementations.

treewide: cleanup from blas/lapack changes

A few issues in the original treewide:

- can’t assume blas64 is a bool
- unused commented code

pkgs/applications/science/molecular-dynamics/lammps/default.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchFromGitHub
-, libpng, gzip, fftw, openblas
+, libpng, gzip, fftw, blas, lapack
 , mpi ? null
 }:
 let packages = [
@@ -27,7 +27,7 @@ stdenv.mkDerivation rec {
     inherit packages;
   };
 
-  buildInputs = [ fftw libpng openblas gzip ]
+  buildInputs = [ fftw libpng blas lapack gzip ]
     ++ (stdenv.lib.optionals withMPI [ mpi ]);
 
   configurePhase = ''